View Full Version : string height at 12th fret?

Jun-10-2006, 9:37am
What is the normal string height at the 12th fret? A mandolin I recent aquired has a string height of about a heavy 3/16 of an inch. Granted I don't play much that far up the neck but I do go up to the 7th a lot and it starts to seem like I am pushing through a lot of string if you know what I mean.

The fretboard is perfectly flat. And I have the bridge adjusted down as low as it will go. Half a turn on either wheel and the strings buzz. The nut has been changed so is maybe the nut too low? Should I shim it up a bit and then try to lower the bridge?

Or should I adjust the trussrod and pull a slight recurve in the neck and then adjust the bridge down?

And does this mean I will soon need a neck reset? And how do you know when you need one other than string height is too high.

Can't take it too a Luthier because there isn't one around here and so I have to do my own set ups and so far I have never had a problem doing so.

I'll leave it alone if the string height at the 12th fret is OK

Jun-10-2006, 10:00am
3/16" is a high.
Except for maybe the G string, 3/32" is getting a little high, but some bluegrassers, in particular, like the G up there so it doesn't buzz as much.
You should be able to lower the E to about 1/16", or even slightly lower and have the height graduate to a little under 3/32" at the G. If fret buzzes start at just below 3/16", there's trouble in the neck.
There should be a slight forward bow in the neck. By that I mean a concavity in the fingerboard from the nut to about the 12 fret area. If it's bowed the other way, or perfectly flat, loosening the truss rod will help, if the truss rod works.
If the extender rises from the plane of the fingerboard toward the bridge, that can cause buzzing at otherwise normal action heights. Correcting that goes beyond set up, and into repair.
If the nut height is correct, and the neck bow is correct, and the strings buzz at 1/16" to 3/32" action at the 12th fret, you need fret work.

Jul-14-2006, 9:36am
I've been lurking on this board for 2 years now so I thought I might as well sign up and join the fun http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif The action topic is one that I've been revisiting quite often. I have taken my mandolins from as low as they could possibly go to way heigher than I ever want to be. I have found the hieght that suits me but would like to know what the action ranges are. My questions to satisfy my curious mind are these:
What height range would you consider to be low action?
What height range would you consider to be medium action?
What height range would you consider to be high action?
Thanks in advance for your information.

Mario Proulx
Jul-14-2006, 11:24am
I am currently running mine at .024" on the first pair, to .028" on the low pair, at the 12th fret. It'll buzz quite readily, but I can play it buzz-free for the most part. I'd consider this as "very low" action. Not jamming action at all, but lovely to play, around the house, or in a 3-4 person 'jam'...

I consider .035" - .040" as low, .060 - .065" as medium, and .090" as high(too high, even).

Jerry Byers
Jul-14-2006, 11:35am
For those of us with rulers, I generally set 7/64" on the G string/12 fret and 5/64" on the E string/12 fret as a standard height. For many, that may be a little on the high side. From here, I can lower it down until I reach the buzz and then ease off from there.

Mario Proulx
Jul-14-2006, 11:44am
For those of us with rulers,

A set of automotive "feeler gauges" costs less than a good ruler, and can be had at any NAPA or Auto Zone type place, and can accurately and easily measure to a .001" tolerance....

To convert fractions to decimals, simply divide. Example: 5 over 64 equals .078", 7 over 64 is .109", etc....

Jerry Byers
Jul-14-2006, 11:52am
I have a good set of micrometers, but I always use my trusty 6 inch shop ruler. I have had that thing for a zillion years.

One other trick that I do, and it seems to work for me. I'll take tension off all the strings except for the outside strings. I'll set those two strings to the measurements I mention and then bring all the strings back up to tension. Under full tension, the top will compress slightly and the bridge will lower about 1/64" to 2/64". This brings the strings to a nice height.

Steve Farling
Jul-14-2006, 12:05pm
I don't know if anyone is interested or not, but I use the plain end of a drill bit laid on the fret board to set the string height. Works great for me!

Paul Hostetter
Jul-14-2006, 1:14pm
Any particular drill bit?

Jul-15-2006, 7:34pm
I have asked a similar question 'here' before, particularly regarding using devices to establish exact measurements on different locations on and above the fretboard. I subsequently received a number of smart and dismissing comments, basically saying that I should not worry about string action; if it feels right it is right. I am a little relieved that other players on this forum have similar concerns to me. If you have established that the action on your instrument is a little too high and the bridge has been lowered as much as possible, what would be the next step for you? Would you now proceed to adjust the truss rod and how would you go about that?

Mario Proulx
Jul-15-2006, 7:53pm
The truss rod is for adjusting the neck relief, and only for adjusting the enck relief. Do not use it to tweak the action! Fopr what its worth, I like my mandolin necks dead straight. No relief at all.....

Set your relief, then adjust the nut slots, -then- go to the bridge and start adjusting. If you run out of adjustment and stil aren't as low as you wish, pull the bridge off, remove the saddle, and mill the area where the adjusting wheels sit. Depending on how low you need to go, you may need to mill the bottom of the saddle itself.

Jul-15-2006, 10:02pm
Thanks 'M', I considered adjusting the truss rod only as the last resort, but on your advice I won't change the setting. I have had this (Canadian) handmade mandolin for 3 years now and with the bridge lowered as low as it can be, the action at the 12th fret (G String) is still .090. I kept the mandolin in its (Pegasus) case when not being played and it has not been exposed to dramatic climatic conditions. It seems from the other input on this subject, that this instrument was set up by the builder on the very high action side in the first place. When I get the opportunity to have the bridge modified by a competent local luthier, I will have that done as a priority. Once again, thanks for your advice.

Mario Proulx
Jul-15-2006, 11:14pm
Thanks 'M'

Ah, my name's Mario. for some reason, the forum software kept saying my name was already in use when I first signed up, therefor, I've not been able to use my name to sign-in.

Action's at .090"? You could, for now(until you have a chance to have it looked at by your luthier of choice), try taking the adjusting wheels completely out and putting the bridge back together. That would bring it right down to about .060"-.070"...

Jul-16-2006, 2:00am
....Unfortunately, the bridge on my mandolin would not go any lower by removing the wheels, Mario. It looks like a complete exchange or alteration of the top part might be neccessary.

Jul-16-2006, 2:03am
..... and there it is, my SMD gauge at the 10th and 12th fret. Quite high action, is it not?

Mario Proulx
Jul-16-2006, 9:46am
Hmmm, you may have a neck angle issue. That bridge and saddle look pretty low already. Yes, yiou can shave some off the bottom of the saddle to get the action 'down there', but for sure, have this mandolin looked at by someone competent. The neck may need a reset. If the enck angle is deemed okay, and the mandolin solid(no issues), then a new/modified bridge and/or saddle will fix you right up.

A picture's worth a thousand words, ain't it? Nice shots...

Jerry Byers
Jul-16-2006, 9:53am
Is this the original bridge? If you're not comfortable shaving the bottom of the saddle, there are short bridges available as a replacement.

Also, you may want to check your neck again. That last photo shows an upward bow when a ruler is put against it - could be an optical illusion from the lens.

Jul-16-2006, 7:03pm
Thanks again. Yes, the bridge is original and the upward bow on the radiussed fretboard probably is an optical illusion caused by the Sony T9 (great little camera) lens. As a lay person, when it comes to mandolin care, I am assuming that a neck reset is different from a tross rod adjustment. Also playing the banjo a bit, the neck on the 5-string is vertically and horizontally somewhat adjustable. However, the neck on the mandolin is set. I just hope that a neck reset does not mean, having the neck removed and re-fitted (re-glued). http://www.mandolincafe.net/iB_html/non-cgi/emoticons/rock.gif

Mario Proulx
Jul-16-2006, 7:29pm
I just hope that a neck reset does not mean, having the neck removed and re-fitted (re-glued)

Yes, that is what that means. BUT! You do have a good bit of bridge height, there, so the odds of that being called for are slim enough. I didn' mean to panic you, but if the action's on the high side and the bridge on the low side, there could be something loose or coming loose. Caught early-on, it is usually an easy repair.

Could be that the builder wanted it that way, also. Have you contacted them? Some might consider this action height as "normal", perhaps, and built accordingly....

The action is still correctable by means of the bridge and/or saddle. I simply want you to be sure that all is solid, also, and that nothing is sneaking up on you.

Jan-01-2011, 10:33pm
Excellent topic and a very helpful thread!! Thanks everyone!


Jan-01-2011, 11:28pm
Most mandolin bridge feet have a lower area between the adjusting wheels so the saddle can be lowered to it's full extent. Your mandolin bridge does not have this and could easily be added allowing your saddle to go lower as it looks like there is room on the wheels to adjust it lower. I also like the bottom of the saddle notches the same as the adjusting wheels and yours is taller so that could be shaved also. If you need more as Mario said take it off under the adjusting wheels, but without doing the other things it won't make any difference. You should be able to make this bridge work for a much better action with a few adjustments.